Dr. Reiss [Dubner's dentist] told me that tooth decay in general, even among wealthy patients, is getting worse and worse, particularly for people in middle age and above. The reason? An increased reliance on medications for heart disease, high cholesterol, depression, etc. Many of these medications, Dr. Reiss explained, produces drymouth, which is caused by a constricted salivary flow; because saliva kills bacteria in the mouth, a lack of it means increased bacteria, which leads to increased tooth decay. Given the choice of taking these medicines versus having some tooth decay, I’m sure most people would still choose the medicines–but I am guessing that most people haven’t thought about the link between the two.